Fix OLC decoding

CHANGELOG.md

@@ -4,6 +4,8 @@ Note: you may refer to `README.md` for description of features.
 
 ## Dev (WIP)
 
+Fixed decoding of OLC producing out-of-bounds coordinates (https://github.com/Vectorial1024/open-location-code-php/pull/6).
+
 ## 1.1.3 (2026-04-21)
 
 GitHub security advisory (https://github.com/advisories/GHSA-qrr6-mg7r-m243)

src/CodeCalculator/CodeCalculatorFloat.php

@@ -81,7 +81,7 @@ protected function generateCodeArea(string $strippedCode): CodeArea
         // Define the place value for the digits. We'll divide this down as we work through the code.
         $latPlaceVal = self::LAT_MSP_VALUE;
         $lngPlaceVal = self::LNG_MSP_VALUE;
-        for ($i = OpenLocationCode::PAIR_CODE_LENGTH; $i < min(strlen($strippedCode), OpenLocationCode::MAX_DIGIT_COUNT); $i += 2) {
+        for ($i = 0; $i < min(strlen($strippedCode), OpenLocationCode::MAX_DIGIT_COUNT); $i += 2) {
             $latPlaceVal = floor($latPlaceVal / OpenLocationCode::ENCODING_BASE);
             $lngPlaceVal = floor($lngPlaceVal / OpenLocationCode::ENCODING_BASE);
             $latVal += strpos(OpenLocationCode::CODE_ALPHABET, $strippedCode[$i]) * $latPlaceVal;

src/CodeCalculator/CodeCalculatorInt.php

@@ -83,11 +83,11 @@ protected function generateCodeArea(string $strippedCode): CodeArea
         // Define the place value for the digits. We'll divide this down as we work through the code.
         $latPlaceVal = self::LAT_MSP_VALUE;
         $lngPlaceVal = self::LNG_MSP_VALUE;
-        for ($i = OpenLocationCode::PAIR_CODE_LENGTH; $i < min(strlen($strippedCode), OpenLocationCode::MAX_DIGIT_COUNT); $i += 2) {
+        for ($i = 0; $i < min(strlen($strippedCode), OpenLocationCode::MAX_DIGIT_COUNT); $i += 2) {
             $latPlaceVal = intdiv($latPlaceVal, OpenLocationCode::ENCODING_BASE);
             $lngPlaceVal = intdiv($lngPlaceVal, OpenLocationCode::ENCODING_BASE);
             $latVal += strpos(OpenLocationCode::CODE_ALPHABET, $strippedCode[$i]) * $latPlaceVal;
-            $lngVal = strpos(OpenLocationCode::CODE_ALPHABET, $strippedCode[$i + 1]) * $lngPlaceVal;
+            $lngVal += strpos(OpenLocationCode::CODE_ALPHABET, $strippedCode[$i + 1]) * $lngPlaceVal;
         }
         unset($i);
         for ($i = OpenLocationCode::PAIR_CODE_LENGTH; $i < min(strlen($strippedCode), OpenLocationCode::MAX_DIGIT_COUNT); $i++) {

test/OpenLocationCodeTest.php

@@ -46,6 +46,8 @@ public function testCorrectCodeFromCoordinates(float $latitude, float $longitude
         $resultCode = $floatCal->encode($latitude, $longitude, OpenLocationCode::CODE_PRECISION_NORMAL);
         $this->assertEquals($resultCode, $expectedCode);
         $resultCodeArea = $floatCal->decode($expectedCode);
+        $this->confirmCoordinatesValidity($resultCodeArea->northLatitude, $resultCodeArea->eastLongitude);
+        $this->confirmCoordinatesValidity($resultCodeArea->southLatitude, $resultCodeArea->westLongitude);
         $this->assertTrue($resultCodeArea->contains($latitude, $longitude));
         if (PHP_INT_SIZE >= 8) {
             // at least 64-bit, which means we can use "long" ints here
@@ -57,6 +59,16 @@ public function testCorrectCodeFromCoordinates(float $latitude, float $longitude
         }
     }
 
+    private function confirmCoordinatesValidity(float $latitude, float $longitude): void
+    {
+        // check latitude
+        $this->assertGreaterThanOrEqual(-90, $latitude);
+        $this->assertLessThanOrEqual(90, $latitude);
+        // check longitude
+        $this->assertGreaterThanOrEqual(-180, $longitude);
+        $this->assertLessThanOrEqual(180, $longitude);
+    }
+
     public static function codeValidityProvider(): array
     {
         return [
@@ -76,7 +88,7 @@ public static function encodingProvider(): array
             "Changi Airport, Singapore" => [1.357063, 103.988563, "6PH59X4Q+RC"],
             "International Antarctic Centre, Christchurch" => [-43.489063, 172.547188, "4V8JGG6W+9V"],
             "Christo Redentor, Rio de Janeiro" => [-22.951937, -43.210437, "589R2QXQ+6R"],
-            "New Chitose Airport, Chitose" => [42.786062,141.680937, "8RJ3QMPJ+C9"],
+            "New Chitose Airport, Chitose" => [42.786062, 141.680937, "8RJ3QMPJ+C9"],
             "Berling Strait" => [65.759937, -169.149437, "92QGQV52+X6"],
             "Null point" => [0, 0, "6FG22222+22"],
         ];